Introduction to Linux

Where does Linux come from, and why are there so many different versions? This module clarifies the difference between the Linux kernel and a distribution, and how Ubuntu, Debian, Fedora, and RHEL differ in target audience and package format. You will learn why open-source licensing matters for enterprises and which distribution fits which use case.

Not every Linux looks the same. You install Ubuntu in the cloud environment and compare the desktop environments GNOME, KDE Plasma, and Cinnamon side by side. You will see which interface offers the smoothest transition for Windows users and where the differences to Explorer, Taskbar, and Control Panel lie.

From here on, you type. You open the terminal, learn the difference between shell and terminal emulator, and run your first commands: pwd, ls, cd, mkdir, cp, mv, rm. If you have used the Windows command prompt or PowerShell before, you will see the direct equivalents and understand why the Linux command line is structured differently.

Linux has no drive letters. Instead, everything hangs under a single root directory /, and each folder has a fixed purpose: /home for user data, /etc for configuration, /var for logs, /tmp for temporary files. You navigate through the structure, understand absolute and relative paths, and see how symlinks differ from Windows shortcuts.

Open files without launching an editor: cat, less, head, and tail display content in different ways. With find you search for files by name, size, or modification date. grep filters text lines by pattern. By the end of this block, you can search a log file for specific error messages.

On Windows many people work as administrator; on Linux you consistently separate regular user from root. You create users with useradd, manage groups, and set file permissions with chmod and chown. Along the way you learn the rwx model (read, write, execute) and understand why sudo is the secure way to gain root privileges.

Editing configuration files is part of everyday Linux work. You start with nano as a beginner-friendly editor: open, edit, save. Then you switch to vim, the standard editor on nearly every server. You practice the key modes (Normal, Insert, Command) and commands (i, :wq, dd, /search) directly on a real configuration file.

What is running on the system, and how do you stop a hanging process? With ps, top, and htop you see running processes in real time. kill and killall terminate processes. Then you learn systemctl: the central command to start, stop, and troubleshoot systemd services.

How does the system access the network, and how do you connect to a remote server? You check network interfaces with ip addr, test connectivity with ping, analyze open ports with ss, and fetch data with curl. Then you set up your first SSH connection, copy files with scp, and configure SSH keys for passwordless login.

On Linux you do not install software via .exe downloads but through package managers. You compare apt (Debian/Ubuntu), dnf (Fedora/RHEL), and see how Snap and Flatpak complement each other as cross-distribution formats. By the end you can search, install, update, and remove packages and know when to use which format.

Bash is the standard on most Linux systems; ZSH is the default on macOS and popular among developers. You compare both shells hands-on: auto-completion, syntax highlighting, globbing, and plugin systems. Then you configure .bashrc and .zshrc, install Oh My Zsh, and customize your prompt. By the end you know which shell fits your workflow.

Repetitive tasks belong automated. You write your first Bash script with shebang line, variables, and echo. Then come control structures: if/else for conditions, for and while loops for repetition. Exit codes ($?) tell you whether a command succeeded. By the end you automate a simple task that previously required multiple manual steps.

The Unix philosophy in one sentence: small programs that do one thing well, chained via pipe (|). You combine grep, sort, cut, wc, and awk into one-liners that answer complex questions about log files. On top of that come redirects (>, >>, 2>&1) to route output to files or capture errors selectively. This way of thinking is one of the most powerful concepts that sets Linux apart from other operating systems.

Modern CLI tools do not replace Unix fundamentals, but they can make search, navigation, and output easier to read. You solve a prepared file search with classic commands and the provided alternatives, filter the result with fzf, and configure an alias plus a Starship prompt. Comparing both approaches shows when an enhancement helps and when portable standard commands are preferable.

Now everything comes together. You work on a realistic task that combines all topics from the past three days: create users and set permissions, write a Bash script that searches log files for errors and formats the results, then transfer the output via SSH to a remote server. Along the way you use pipes, redirects, and the CLI tools you have learned.